MXPA06014634A - Mica tape having maximized mica content. - Google Patents

Abstract

An electric insulating material according to the invention is composed of a glass fiber layer with a mica layer disposed thereon. The glass fiber layer includes twist-free glass yarn. It may be a woven glass fabric. The material is particularly suitable for insulating electrical conductors such as wire suitable for use in high temperature environments, and coils for use in high voltage electrical motors and generators.

Description

MICA TAPE WHICH HAS MAXIMIZED MICA CONTENT CROSS REFERENCE WITH RELATED APPLICATIONS This application requests the priority of the United States provisional application serial number 60 / 580,489, filed on June 16, 2004, the total content of which is incorporated herein by reference. BACKGROUND OF THE INVENTION Electrical insulating conductors in electrical appliances have undergone significant improvements since the development of the first machines in the nineteenth century. As demands were made to supply larger and more efficient machines for industrial and commercial application, the insulation systems employed by the designers evolved to provide more strength of resistance and still occupy less space in the machine. It should be remembered that most electrical machines are made of an electrically conductive material, a magnetic material and an insulation system. Basically, the magnetic material and the electrically conductive material are the two active materials that determine the operation of the machine and the production capacity and the insulation is only present to ensure that the electricity flows only in predetermined paths. Thus, the necessary insulation must occupy a minimum of space and still provide the necessary insulation between the adjacent electrical conductors and between the conductors and any adjacent material that are in potential ground connection. In the past, electrical machines have traditionally used varnish, enamel compounds or glass wrap to cover individual conductors that supply the required primary strand or "turn-by-turn" insulation for individual conductors. In especially rotating machines, the previous conductors are rewound in coils, and each coil is provided with a second insulation means, and this insulation is in the form of an insulating tape or a cover wrapped around the group of individual conductors that have been formed from a predetermined way to form a coil. The varnishes that function satisfactorily in the first lower voltage machines were gradually overcome by enamels and more recently by polymeric materials such as polyesters, polyesteramides, polyesteramideimides and polyimides to mention just a few commercially available conductor coatings. The coil insulation has evolved from the cotton tape wrapped in layers in an overlapping manner to provide the necessary insulation to an asphalt insulation comprising overlapping coils with a tape coated with a petroleum base compound which was subsequently coated with a layer of mica lamellae. The mica lamellae provided an insulation resistance to phenomena generally known as "corona" that tend to become more problematic when the operating voltage levels of the rotating machines were increased. Gradually, the glass fiber tapes came to be used as a carrier carrier for the mica lamellae and a host of polymeric materials was used to provide the adhesive forces necessary to hold the mica lamellae in place on the tape. These are commonly known as mica tapes. In a process the coil is rewound through conventional imbricate winding techniques indicated and subsequently placed in a coil-forming device. A vacuum pressure impregnation process (VPI) is used to impregnate the taped coil with a suitable insulation material such as uncured polymeric material to fill all gaps and interstices in the overlapping insulation, and the coil is heated to harden the coil and insulation compounds through a polymerization process. An alternative process to isolate the coils of electrical machines is to rewind the coil or the strands with a stratified tape that has been literally covered with a polymer polymer of stage "B" in a conventional way of superposition, until the desired number of turns has been applied to the coil or stump and then applying heat and pressure at a temperature with limits from about 160 ° C to about 180 ° C to the coil or stump to conduct the polymeric material or solidification. During the heating and compression operation, the viscosity of the polymeric material of stage "B" drops initially and the excess resin is compressed from the coil by the press used to give the coil its final shape. The mica tape differs in composition according to which the process of manufacturing the insulated coil is used. For VPI processes, ribbons having relatively low resin content are used. The tapes are dry, flexible and non-adhesive tapes and are distinguished by exceptional absorption capacity. Consequently they are used for high voltage machines (up to 1000 MVA). To prepare the tapes that are capable of being impregnated, a mica paper is impregnated with an epoxy resin in solvent medium and then combined with a support. Alternatively, a solid resin can be powdered either in a mica sheet or directly in the support, and then the two compounds can be laminated together under pressure and heat. The resin content is typically between 3% and 25%, based on the total weight of the tape. For non-VPI process, the tapes are typically made of mica paper which is impregnated in an amount with epoxy resin. The resin content is usually between 25% and 50% in relation to the total weight of the belt. During manufacture, the epoxy resin partially hardens to state B. In high-voltage generators, such as those used to generate electricity, or high-voltage motors, the increasingly demanding requirements for the resistance voltage of any given material for the insulation they are giving rise to an increase in the thickness of the insulation and in the number of coiled layers. However, as the thickness increases, the heat transfer between the winding and the laminated stator core deteriorates at the same time, and this leads to problems in the dissipation of heat losses. In addition, for any given stator geometry, the winding must be designed with a smaller conductor cross section, resulting in a reduction of the energy generated. Consequently, an object of the invention is to provide an improved insulating material having both improved dielectric utilization (non-disruptive voltage) and improved thermal utilization (heat resistance). SUMMARY OF THE INVENTION It has been unexpectedly discovered that a mica / glass fiber composite based on a fiberglass layer composed of non-twisted yarn has improved the insulating properties when used in large electrical machines or to insulate wire at very high temperature. high. In one aspect, then, the present invention relates to an electroinsulating material including a layer of fiberglass and a mica layer placed thereon, wherein the fiberglass fabric comprises a non-twisted yarn. DETAILED DESCRIPTION The present invention relates to an electroinsulating material that includes a layer of glass fiber and a mica layer placed on the fiberglass layer and the glass fiber layer is composed of a non-twisted yarn. The fiberglass layer can be a fiberglass cloth, especially a woven fabric or it can be a layer of parallel fiberglass filaments or yarns. In a preferred embodiment, the electroinsulating material is a mica ribbon. The glass fibers for use in the electrical insulating material of the present invention are composed of torsion-free glass fiber, also referred to as unbranched or zero-twisted, spun, as described in U.S. Patent No. 6,581,257, to Burton. and collaborators, all the content of which is incorporated herein by reference. The patent discloses a process for manufacturing a warp bead from non-twisted strands. In conventional process that produces twisted wire, the fastener of the yarn package is fixed so that the yarn rotates around the outside or the inner circumference of the package, and a twist is imparted to the yarn. In the Burton patent process, the spin pack is rotated at the line speed of the operation. The yarn is unwound so that the spinning bundle does not twist or impart a twist to the yarn. This yarn can be used to weave a fabric that is thicker and stronger, while producing products with improved electrical and thermal properties compared to conventional fiberglass fabrics composed of braided yarns. The yarn without twist resembles the ribbon, rather than a rope, with respect to conventional braided yarns, and produces a flatter and thicker fabric with a smooth surface. The fibers that make up the yarn are typically only about 5 microns in diameter. The process for making a fabric from non-twisted yarn is also different from conventional processes for weaving glass fiber yarn in that the end of the fabric finish can be applied when the fibers are unwound from the package. This results in a cleaner fabric that is at least as strong as in fabrics made from conventional spinning. The fiberglass layer is typically a woven glass fiber cloth, although non-woven fabrics can be used when the fabric is sufficiently strong and thin. Filaments or threads composed of yarn without torsion can also be used in the fiberglass layer, in this case, the electrical insulating material of the present invention is a mica ribbon of the filament type. A woven fabric that is particularly suitable for use in the electrical insulating materials of the present invention can be obtained from Dielectric Solutions, East Butler, under the brand name GlasFab® as the fabric style 1297 or 1299. Electroinsulating materials and in particular Micas ribbons, composed of torsion-free fiberglass yarns offer important advantages that are not easily obtained with traditional braided yarns. Especially in insulation for windings of electric motors and high temperature and high voltage wires for use in high temperature environments. These advantages include higher mica content in the tape with the same thickness as conventional tapes, or thinner insulation for the same mica content, high tensile strength, lower resin content and improved fatigue limit to the voltage. Non-twisted yarns are flatter than twisted yarns when woven into a fabric and the fabric is thinner than a fabric composed of braided yarns. This means that for a given final thickness of a typical fiberglass cloth / mica paper composite, more mica paper can be added to the construction. Because it is the mica paper that provides the desired characteristics of the insulating compound, it may be desirable to substantially increase the mica content. For example, a typical construction would be 2 mils of fiberglass cloth and 3 mils of mica paper. By using the fabric composed of non-woven yarn, the same construction can be redesigned for a 1.2 mil fabric and 3.8 mils of mica paper. This is a 27% increase in mica content. Another way of looking at this is to evaluate the proportions of mica for fiberglass. In the first example, the mica ratio for glass fiber is 1.5 compared to 3.2 for the flat spinning example. Such an increase in the primary insulation component may allow the manufacturers of motors and generators to increase the stress on the insulation and add more copper in the design. For a given machine size, more power output can be allowed. In other cases, it may be convenient to reduce the thickness of the insulation. Thinner wall insulation in generator coils can improve thermal conductivity and allow the unit to operate in a colder state, which can translate into an improved operating life.

Replacing a fiberglass cloth is typical with a composite of non-twisted yarn, a thinner insulating material can be produced, without sacrificing the mechanical or electrical properties, in particular the tensile strength. The non-twisted filaments are not cut with each other at the cross-over of the pattern and therefore a thinner fabric typically has higher tensile strength than a cloth of the same thickness and which is composed of braided yarns. In the composite form, this means that the improved proportion of mica for glass fiber is not carried out by sacrificing the tensile strength, as would be the case for glass fiber fabrics based on traditional round yarn. This is important in that mica paper fiber glass composites require greater traction for final use by the customer. The non-twisted filaments provide a considerably greater surface area for bonding the fabric to the mica paper than the yarn-based fabric allows. The bond in the interconnection between the fiberglass fabric and the mica paper is often a point of defect during customer application. Therefore, we try to maximize this interconnection union. The natural geometry of the non-twisted yarn in the fabric produces a considerably improved bond in fabrics based on braided yarn. The total resin content that is used in the electroinsulating material according to the present invention for mica paper is typically less than in conventional materials, because the volume of the glass fiber layer is lower. This can result in a reduction in costs. In addition, a reduction in organic volume typically results in improved fatigue limit voltage performance of this insulation and better thermal conductivity of the insulation. For the electroinsulating material of the present invention, a mica layer is typically laminated with the glass fiber layer by means of at least one polymer resin, and commonly two or more resins are used to bond the mica layer to the fabric fiberglass The polymeric resin can be a thermosetting resin, in particular an epoxy resin. In a preferred embodiment, the mica layer and the glass fiber cloth are each impregnated with an epoxy resin bearing solvent of different molecular weight and then bonded together. The mica layer of the electroinsulating material of the present invention is typically in the form of mica paper, although mica lamellae, lamellar paper or mica flakes can also be used. Muscovite mica or phlogopite are commonly obtained and used. The phlogopite has superior thermal properties and coefficient of thermal expansion. The mica paper can be a calcined mica paper or disintegrated paper - integrated in water (not calcined). A typical manufacturing process for the calcined paper is as follows: First, a micaceous mineral is calcined at, for example 700-1000 ° C, to remove foreign matter and crushed into pieces of predetermined size. Jet water is then applied to the mica pieces, thus producing fine mica particles. The mixture is combined in water, leading to a mica dispersion. After which, the dispersion is subjected to a papermaking process to make a paper in a cloth and dried to obtain a mica paper. The thickness of the mica layer is the electroinsulating material of the present invention which typically ranges from about 2 mils (50 μm) to about 10 mils (250 μm), preferably about 2 mils to about 6 mils (150 μm) to use it in wrapping the coils and half rods where the compound acts as the main earthing insulator. To wrap individual conductors on tape, a thin ribbon is convenient in these applications, the thickness of the mica layer typically ranges from about 0.5 mils (12 μm) to about 10 mils, preferably about 1 mil to about 4 mils (100 μm) and more preferably from about 1 mil to about 3 mils. The thickness of the glass fiber typically ranges from about 0.5 mils to about 10 mils, preferably about 0.8 (20 μm) to about 5 mils (125 μm). The resins for use in the manufacture of electroinsulating material of the present invention are chosen in accordance with the performance criteria required for final use, including the thermal, mechanical and electrical properties of the resin. For example, IEEE 275 stipulates a procedure to evaluate the electrical mechanical properties of laminates under conditions ter, aging or mechanical stress; other methods are known in the art. Any resin system can be used as long as it is chosen using firm engineering criteria. Suitable resin systems include thermoset epoxy resins, especially novolac phenolic epoxy resins, butadiene-based resins, polyesters, silicones, bismaleimides and cyanate esters. Examples of suitable epoxy resins include bis (3,4-epoxy-6-methyl-cyclohexyl methyl) adipate, vinylcyclohexane dioxide or glycidyl esters of epoxy resin of polyphenols such as epoxy resin of bisphenol A diglycidyl ether epoxy resin of phenol formaldehyde novolac polyglycidyl ether, epoxy cresol novolac or mixtures thereof. The resin content may vary from about 3% to about 25% by weight, preferably from about 5% to about 18% by weight in tapes for use in a VPI process. For processes that require tapes having a higher resin content, the resin content typically ranges from about 25% to about 50% by weight, preferably from almost 27% to almost 45% by weight. In some embodiments, the electroinsulating material of the present invention further contains a compound or composition capable of accelerating the hardening of an epoxy-anhydride resin system. These materials are used in VPI processes, where the micas tapes with accelerators in them are impregnated with an epoxy resin of VPI that contains the acid anhydride. The accelerator is in the tape in a stoichiometric ratio based on the anhydride of the epoxy resin of VPI. Typical metal accelerators include zinc naphtannate, zinc octoate, copper octoate, chromium octoate and stannous octoate. Tertiary amines such as tris (dimethylaminomethyl) phenol are also effective as are imidazoles such as ethylmethylimidol. The anhydrides in the resin may include: maleic anhydride adduct of methylcyclopentadiene (nadic methyl anhydride), nadic anhydride, hexahydrophthalic anhydride, dodecenyl succinic anhydride, ophthalmic anhydride and pyromellitic anhydride. The electroinsulating material of the present invention can be manufactured by any of the conventional processes known in the art. Such processes are described in U.S. Patent Nos. 4,704,322, U.S. 4,286,010, and U.S. 4,374,892, the contents of which are incorporated herein by reference. A basic process for the production of a mica tape according to the present invention is to impregnate the mica paper and / or the glass fiber cloth with a resin and laminate the two. A polymer film, such as a polyester or polyimide, can be included in the electroinsulating materials of the present invention, typically on one or both of the outer surfaces thereof. A polymeric mat can also be used, instead of or in addition to, the polymeric film. The polymeric mat is typically composed of a non-woven fabric, especially a non-woven polyester fabric, having a thickness of about 0.8 to 3 mils. The film or mat protects the mica from damage layer during tape wrapping. In addition, it may be beneficial to provide protection against deterioration of the corona of the insulation of individual conductors and in that way, a resistant material of corona can be added to the insulating materials for some applications. U.S. Patent No. 5,989,702 and Canadian Patents 1,168,857, and 1,208,325 provide examples of the addition of various compounds such as particles of submicron size of alumina or silica to polymer compositions used to cover individual conductors or to polymeric films. DuPont's KAPTON® CR is an example of a suitable polymeric film containing corona-resistant material. The addition of alumina or silica particles can also increase the heat transfer characteristics of the conductor insulation as well. A process for manufacturing an insulated electrical conductor in accordance with the present invention includes wrapping the electrical conductor within an electroinsulating material, as described above, especially a mica tape and heat the wrapped conductor to harden the resin. In particular, conductors such as coils for rotating electrical machines can be wound up by conventional winding techniques and placed in a coil-forming device. A VPI process can be used to impregnate the ribbon wrapped coil with a suitable insulation material such as an uncured polymer resin to fill the spaces and interstices of the overlapping insulation. The coil can then be heated to harden the composite coil and the insulation through a polymerization process. Another process is to wind the bobbin with a mica tape in an overlap mode, until the desired number of turns has been applied to the bobbin or stump, and then apply heat and pressure to the bobbin or stump to bring the polymeric material to the coil. gelation During the heating and compression operation, the viscosity of the polymeric material of stage "B" in the belt typically falls off initially and the excess resin is squeezed from the coil by the press employed to give the coil its final shape. To insulate individual wires using mica paper / fiberglass cloth composite, thin glass fiber can be harnessed to produce the thinnest convenient insulation. Again, for the same allowed space, thinner insulation will allow more copper, without reducing the amount of mica in the insulation, which translates into more power output. In addition, due to the high tensile strength of the glass fiber fabric, the tensile strength of the composite insulation is the same as that of conventional, or even larger, mica tape, which is used as cable insulation. Fabrics based on twisted yarn in mica compound cause firm edges in the wrapped conductors. Non-twisted yarn produces a smoother, thinner wrap. In the case of insulated round wire, the smooth surface is convenient when molded by injection onto the conductor. The final extruded layer on the cable can be thinner and smoother. Resins for use in high temperature cable insulation are selected to operate under high temperature conditions of use and are typically silicone resins, although any resin that meets the performance criteria for the application can be used. A cable, wire or conductor layer operating at high temperatures can be prepared by wrapping a conductor like a copper wire with a mica tape according to the present invention. In some applications, the set of wrapped parts can be heated to harden the resin in the mica tape. Electroinsulating materials for high temperature wiring are typically based on silicone resins. U.S. Patent No. 4,034,153 and 6,079,077 disclose a process for manufacturing insulated wire using conventional mica tapes and are incorporated herein by reference. It should be noted that the layers of plastic film and / or additional layers of mica tape, as described in US Pat. No. 4,034,153, are necessary in a process for preparing an insulated cable in accordance with the present invention. High-temperature electrical conductors typically meet the requirements of UL 5107.5127 or 5128 or IEC 331 or 332, and can operate at temperatures up to 450 ° C and preferably up to 600 ° C for connection of appliances and conductive wire, and up to 750 ° C and preferably up to 1000 ° C, for power cables, command cables, signal cables and controls, high temperature cables and fire resistant wires and cables. These conductors are widely used in offshore vessels and platforms and in tunnels or steel structures and nuclear power plants. EXAMPLES EXAMPLE 1 4,086 grams of polybutadiene resin (Lithene AH, Lithium Corporation of America) having an average molecular weight of about 1800 was dissolved in 8.172 grams of toluene containing about 41 grams of dicumyl peroxide hardening agent to give 33.4% by weight solids solution. A sheet with thickness of approximately two mils contacted glass fiber diffuser gauze of approximately 1.2 mils thick GlasFab® Direct by Dielectric Solutions and the polybutadiene resin solution roller covered on and on the mica sheet through of the glass fiber diffuser gauze. This was followed by roll coating a polymeric sealing layer comprising a binder copolymer binder solution A-B-A of isoprenebutadiene in the glass fiber diffuser fabric. The sealant layer in this particular example was melted from a solution comprising 6.7 pounds of toluene, 1.32 grams of an antioxidant (Irganox 101, Ciba Geigy), 0.66 grams of diallylthiodipropanate, 0.66 grams of antioxidant is 618 and 0.58 pounds of an ABA block copolymer of isoprene-butadiene (Kraton 1107). The tape thus coated is heated in platen from below at a platen temperature of about 375 to 450 ° C. After application of the coatings, the tape (tape No. 1) is heat treated in a drying oven at about 325 ° F to a considerably non-tacky state, although in a time interval so that hardening does not start of polybutadiene. At the time of exit from the drying oven, a layer of polyethylene terephthalate film was applied in a thickness of about 0.25 mils to the side of the mica tape opposite the fiberglass diffusing fabric and the compound was run through the calendering rollers hot at approximately 300 ° F. A second sample (tape No. 2) was formed in the same manner as the first sample but including an additional layer of the polyethylene-methaphthalate film in the copolymer layer of the block of the first sample. The polyester layer was applied to the same place in this manner as in the first polyester layer of the first sample. The properties of the respective tape are shown in Table I. Both tapes had a residual solvent content (toluene) of about 0.5% by weight.

Laminates based on other resin systems as described in Table II were prepared. The dissipation factor for the selected laminates was determined and indicated in the table.

* These castings were all made from the acetone solution of the resin. ** Qualified in the class of 180 ° C.

EXAMPLE 2: Tape Lap Test Roll Insulation: 3/4"x 100 yard rolls is the standard package The experimental tape demonstrated excellent placement without the strings seen in the competition tape. : Rolls of 1"x 30 yards in cores with an inside diameter of one inch is the standard package. It was determined that the tape package remained stable throughout the entire tape wrapping process, even at the highest voltage. Again, the tape adhered smoothly and with a very uniform appearance. The coils prepared using the experiment material (coil No. 9) and the two control tapes (coil No. 11 and coil No. 8). The side plates were bolted to the coil groove sections to simulate the saturation constraints encountered when the coil is in the stator. All electrical tests were performed without removing the slot side plates. This tends to give greater tip-up results (high extremes) and dissipation factor values. However, because all the coils were examined in the same way, the results can be considered relative. The shunts of the coils were energized and the dissipation factor was measured in the slot section by connecting the measurement shunt to the side plates.

The resin buildup was removed in all connection areas. The dissipation factor was measured at room temperature and then at an elevated temperature at a voltage of 2 Kv. Each leg of the coil was examined and an average of the two results is reported. The coils were allowed to reach thermal equilibrium by keeping them at the measurement temperature for 1 hour before the evaluation. The results are as follows: Typically in most material combinations they show a low dissipation factor at room temperature. As the temperature of the material increased, in general there was an increase in the dissipation factor. This is a function that the resin in the tape also hardens along with the resin in the VPI tank. In addition, it provides an indication of the general polar nature of the bonding resin in the ribbon itself. The optimum is to have zero increase and in practice, try to minimize this effect. In general, if there is an increase in DF, then an increase in the dielectric constant can also be seen. The increase of the dielectric constant puts greater dielectric stress in the empty areas, which can become a site for discharge of the internal crown and finally insulation defect. The results obtained in coils Nos. 11 and 9 are considered excellent and consistent with the hardened anhydride epoxy system. In addition to measuring the dissipation factor at room temperature, the tip-up (high extremes) between 2 and 8 Kv was measured on each leg of each coil. This measurement was made both before and after the coils were lifted up to 180 ° C. The intent of the tip-up prior to the temperature exposure is to determine what also the insulation accepted the VPI resin. A high tip-up value would reflect poor saturation due to high empty space content. The tip-up after exposure to temperature would reveal problems with thermal stability as a result of degassing and puffing of the insulation wall. The results are the following. None of the coils showed a problem with degassing or puffing. All show an improvement in the dissipation factor after exposure to 180 ° C. This is consistent with an insulation that receives additional hardening. The tip-up are considered normal taking into account the configuration of two electrodes. The electrodes are saved these values would be expected to be very constant. The key point is that there is no increase in the real tip-up for the experiment material (coil No. 9) and that it is consistent with the control. In the coils examined for the dissipation factor, the plate of the groove section was removed and thin cross sections of 0.050"were cut to visually observe the copper alignment, the direction of the insulation and the VPI resin filling All cross sections of the coils showed some degree of distortion in the tape, part of this due to the alignment of the copper, the directional characteristics of the tape itself and the tension of the tape during application.All the sections also showed bags.These bags are not empty and were actually well filled with epoxy resin, as the resin is translucent and the samples light up from behind, these give a deceptive appearance of empty spaces. However all the coils were well filled with VPI resin. This aspect would be considered excellent copper alignment in coils 11 and 8 which was much better than in 9. It seems that less attention was paid in this aspect of the coil preparation due to its nature as samples. EXAMPLES 3: Resin Content - Mica / Fiberglass Proportion The tapes were prepared through the process described in Example 1, using an epoxy resin system. The experiment tape differed from Control 2 only in that Dielectric Solutions fiberglass fabric composed of non-twisted fibers was the one used.

It can be seen that the experiment tape had a higher mica / fiberglass thickness ratio, a lower resin content and a higher tensile strength than any of the controls.

Claims (21)

1. CLAIMS 1. An electroinsulating material comprising a layer of glass fiber and a mica layer placed thereon, wherein the fiberglass layer comprises spinning of fiberglass without twisting.
2. 2. An electroinsulating material according to claim 1, wherein the fiberglass layer is a woven glass fiber fabric.
3. 3. An electroinsulating material according to claim 1, further comprising at least one polymeric resin.
4. 4. An electroinsulating material according to claim 2, wherein the polymer resin comprises a thermosetting resin.
5. 5. An electroinsulating material according to claim 2, wherein the polymeric resin comprises at least one epoxy resin.
6. 6. An electroinsulating material according to claim 2, wherein the polymer resin comprises at least one silicone resin.
7. 7. An electroinsulating material according to claim 3, wherein the resin content ranges from about 3% to about 25% by weight.
8. 8. An electroinsulating material according to claim 3, wherein the resin content ranges from about 5% to about 18% by weight.
9. 9. An electroinsulating material according to claim 3, 7 or 8, further comprising a hardening accelerator.
10. 10. An electroinsulating material according to claim 9, wherein the hardening accelerant comprises a metal or an amine.
11. 11. An electroinsulating material according to claim 3, wherein the resin content ranges from about 25% by weight to about 50% by weight.
12. 12. An electroinsulating material according to claim 3, wherein the resin content ranges from about 27% to about 45% by weight.
13. 13. An electroinsulating material according to any of the preceding claims, in the form of a tape.
14. 14. A process for making an insulated electrical conductor, the method comprising: wrapping the electrical conductor with an electroinsulating material according to any of the preceding claims.
15. 15. A process according to claim 14, further comprising heating the wrapped conductor to harden the resin.
16. 16. A process according to claim 14, wherein the electrical conductor is a suitable wire for use in high temperature environments.
17. 17. A process according to claim 14, wherein the electrical conductor is a coil for use in a high voltage electric motor.
18. 18. A process according to claim 14, further comprising impregnating the material with a thermosetting resin before heating the wrapped conductor.
19. 19. A high temperature insulated yarn manufactured using a process according to claim 16, wherein the yarn is rated for operation at temperatures up to 450 ° C.
20. 20. A high temperature insulated yarn manufactured using a process according to claim 16, wherein the yarn is rated for operation at temperatures up to 1100 ° C.
21. 21. A high temperature insulated wire manufactured using a process according to claim 17.